Methods and devices for occluding an ear canal having a predetermined filter characteristic

ABSTRACT

Occlusion divices, earpiece devices and metods of forming occlusion devices are provided. An occlusion device is configured to occlude an ear canal. The occlusion device includes an insertion element and at least one expandalde element disposed on the insertion element. The expandable element is configured to receive a medium via the insertion element and is configured to expand, responsive to the medium, to contact the ear canal. Physical parameters of the occlusion device are selected to produce a predetermined sound attenuation characteristic over a frequency band, such that sound is attenuated more in a first frequency range of the frequency band than in a second frequency range of the frequency band.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 16/861,344, filed 29 Apr. 2020, which is acontinuation of and claims priority to U.S. patent application Ser. No.16/101,597, filed 13 Aug. 2018, which is a continuation of and claimspriority to U.S. patent application Ser. No. 13/805,833, filed on Apr.15, 2013, which is a National Stage Entry of PCT/US11/41776 filed onJun. 24, 2011, which claims priority to U.S. Provisional PatentApplication Ser. No. 61/358,888 filed Jun. 26, 2010, all of which areherein incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to earpiece devices, and moreparticularly, to methods and devices for occluding an ear canal with apredetermined sound attenuation characteristic over a frequency band.

BACKGROUND

People may be exposed to noise pollution from their ambient environment(for example, from traffic, from construction sites, from aircraft,etc.). People may also be intentionally exposed to high sound levels(for example, from cell phones, MP3 players, home theater equipment,rock concerts, etc.). Studies have shown that ear damage, which may leadto permanent hearing impairment, is not only increasing in the generalpopulation, but may be increasing at a significantly faster rate inyounger populations.

The potential for hearing damage may be a function of both a level and aduration of exposure to a sound stimulus. Studies have also indicatedthat hearing damage is a cumulative phenomenon. Although hearing damagedue to industrial or background noise exposure is more thoroughlyunderstood, there may also be a risk of hearing damage from the exposureto intentional excessive noise, such as with the use of headphones.

Devices which attenuate sound directly to the ear canal are known.Conventional devices typically fit in the ear, around the ear and/orbeyond the ear. Examples of these devices include headphones, headsets,earbuds and hearing aids. Earpieces that occlude the ear canal mayprovide increased attenuation of the ambient environment, offeringimproved sound isolation. However, conventional in-ear earpieces may befitted for a cross-section of a population. Conventional in-earearpieces, thus, may not be properly fitted to the individual user andmay not be adequately sealed, leading to reduced sound attenuation ofthe ambient environment.

SUMMARY OF THE INVENTION

The present invention is embodied in an occlusion device configured toocclude an ear canal. The occlusion device includes an insertion elementand at least one expandable element disposed on the insertion element.The at least one expandable element is configured to receive a mediumvia the insertion element, and is configured to expand, responsive tothe medium, to contact the ear canal. Physical parameters of theocclusion device are selected to produce a predetermined soundattenuation characteristic over a frequency band, such that sound isattenuated more in a first frequency range of the frequency band than ina second frequency range of the frequency band.

The present invention is also embodied in an earpiece device configuredto occlude an ear canal. The earpiece device includes a housing unit andan occlusion section configured to be inserted into the ear canal. Theocclusion section includes an insertion element coupled to the housingunit and at least one expandable element disposed on the insertionelement. The at least one expandable element is configured to receive amedium, and is configured to expand, responsive to the medium, tocontact the ear canal. Physical parameters of the occlusion section areselected to produce a predetermined sound attenuation characteristicover a frequency band, such that sound is attenuated more in a firstfrequency range of the frequency band than in a second frequency rangeof the frequency band.

The present invention is further embodied in a method of forming anocclusion device. The method includes selecting physical parameters ofat least one expandable element and a medium of the occlusion device toproduce a predetermined sound attenuation characteristic over afrequency band associated with an expanded state of the at least oneexpandable element and disposing the at least one expandable element onan insertion element such that the at least one expandable element isconfigured to receive the medium via the insertion element. The at leastone expandable element is configured to expand to the expanded state,responsive to the medium, to contact an ear canal. In the expandedstate, the predetermined sound attenuation characteristic is configuredto attenuate sound in a first frequency range of the frequency band morethan in a second frequency range of the frequency band.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be understood from the following detailed descriptionwhen read in connection with the accompanying drawing. It is emphasized,according to common practice, that various features of the drawings maynot be drawn to scale. On the contrary, the dimensions of the variousfeatures may be arbitrarily expanded or reduced for clarity. Moreover,in the drawing, common numerical references are used to represent likefeatures. Included in the drawing are the following figures:

FIG. 1 is a cross section diagram of an ear illustrating a generalphysiology of the ear;

FIG. 2 is a cross section diagram of an exemplary earpiece deviceinserted in an ear canal, according to an embodiment of the presentinvention;

FIG. 3 is a cross section diagram of a portion of the earpiece deviceshown in FIG. 2, according to an embodiment of the present invention;

FIGS. 4A and 4B are respective perspective view and cross sectiondiagrams of an exemplary earpiece device in an expanded state, accordingto another embodiment of the present invention;

FIGS. 4C and 4D are respective perspective view and cross sectiondiagrams of the earpiece device shown in FIGS. 4A and 4B in a contractedstate;

FIG. 5A is a cross section diagram of an exemplary expandable element ina tube illustrating a change in static pressure, according to anembodiment of the present invention;

FIG. 5B is graph of volume as a function of pressure difference for theexpandable element shown in FIG. 5A;

FIG. 6A is a cross section diagram of an exemplary acoustical system,according to an embodiment of the present invention;

FIG. 6B is an electro-acoustical circuit diagram representing theacoustical system shown in FIG. 6A, according to an embodiment of thepresent invention;

FIG. 7 is a graph of transmission as a function of frequency for theelectro-acoustic circuit diagram shown in FIG. 6B, for variouscapacitance values of an expandable element;

FIG. 8A is a cross section diagram of an exemplary acoustical system,according to another embodiment of the present invention;

FIG. 8B is an electro-acoustical circuit diagram representing theacoustical system shown in FIG. 8A, according to an embodiment of thepresent invention;

FIG. 9 is a graph of transmission as a function of frequency for theelectro-acoustic circuit diagram shown in FIG. 8B, for variouscapacitance values of expandable elements;

FIG. 10A is a cross section diagram of an exemplary acoustical system,according to another embodiment of the present invention;

FIG. 10B is an electro-acoustical circuit diagram representing theacoustical system shown in FIG. 10A, according to an embodiment of thepresent invention;

FIG. 11 is a graph of transmission as a function of frequency for theelectro-acoustic circuit diagram shown in FIG. 10B, for various leaksizes between expandable elements;

FIG. 12A is a cross section diagram of an exemplary acoustical system,according to another embodiment of the present invention;

FIG. 12B is a circuit diagram of a transfer network associated with theacoustical system shown in FIG. 12A;

FIG. 12C is an electro-acoustical circuit diagram representing theacoustical system shown in FIG. 12A, according to an embodiment of thepresent invention;

FIG. 13 is a graph of transmission as a function of frequency for theelectro-acoustic circuit diagram shown in FIG. 12C, for variouscapacitance values of an expandable element;

FIG. 14A is a graph of effective attenuation as a function of frequencyfor various lengths of an expendable element;

FIG. 14B is a graph of effective attenuation as a function of frequencyfor various gauge pressures in an expandable element;

FIG. 14C is a graph of effective attenuation as a function of frequencyfor an expandable element for various tube diameters;

FIG. 14D is a graph of effective attenuation as a function of frequencyfor an expandable element formed from different materials;

FIG. 15 is a graph of effective attenuation as a function of frequencyfor exemplary occlusion sections having one and two expandable elements;

FIG. 16 is a graph of effective attenuation as a function of frequencyfor expandable elements filled with air or water; and

FIG. 17 is a graph of effective attenuation as a function of frequencyfor an expandable element with and without a flange.

DETAILED DESCRIPTION OF THE INVENTION

Aspects of the present invention include methods and devices foroccluding an ear canal which provide a predetermined sound attenuationcharacteristic over a frequency band, such that sound is attenuated morein one frequency range than in another frequency range of the frequencyband. Exemplary earpiece devices of the present invention include anocclusion section having an insertion element coupled to an expandableelement. The expandable element is configured to receive a medium and toexpand to contact and conform to the ear canal. The sound attenuationcharacteristic of the earpiece device may be selected based on physicalparameters of the occlusion section.

Referring to FIG. 1, a cross section diagram of ear 100 is shown, whichillustrates the general physiology of ear 100. An external portion ofear 100 includes pinna 102 and concha 104. An internal portion of ear100 includes ear canal 108 and tympanic membrane 112.

Pinna 102 is a cartilaginous region of ear 100 that focuses acousticinformation from an ambient environment to ear canal 108. Concha 104 isa bowl shaped region in proximity to ear canal opening, indicated bydashed line 106.

Wall 110 (also referred to herein as ear canal wall 110) of ear canal108 forms an acoustic chamber, which terminates with tympanic membrane112. Sound enters ear canal 108 (at dashed line 106) and is subsequentlyreceived by tympanic membrane 112. Tympanic membrane 112 is a flexiblemembrane in the middle ear that couples to components of the inner ear.In general, acoustic information resident in ear canal 108 vibratestympanic membrane 112. The vibration is converted to a signal(corresponding to the acoustic information) that is provided to anauditory nerve.

Ear canal 108 typically includes cartilaginous region 116 (betweendashed lines 106 and 114) and bony region 118 (between dashed line 114and tympanic membrane 112). Cartilaginous region 116 includes a layer ofcartilage underlying the skin layer. Bony region 118 represents an areawhere bone underlies ear canal wall 110. Vibrations may be conductedthrough the bone (in bony region 118), pass through ear canal wall 110,and may be radiated as sound into ear canal 108.

In bony region 118, a skin layer of ear canal wall 110 may be sensitiveto pressure. In general, the skin layer in bony region 118 isapproximately one tenth a thickness of a skin layer in ear cartilaginousregion 116. Thus, in bony region 118, there is little tissue separatingskin from bone. Accordingly, placement of an object (such as an earplug)in bony region 118 can stimulate nerves (due to skin being pressedagainst bone), which can be uncomfortable and even induce significantpain.

In contrast to bony region 118, cartilaginous region 116 is a highlyflexible region having no substantial rigid structure. Thus,cartilaginous region 116 may be more easily deformed when a force isapplied ear canal wall 110 (in cartilaginous region 116). In general,cartilaginous region 116 is much less sensitive to pressure than bonyregion 118.

In general, application of pressure to ear canal wall 110 (such as by anearplug which occludes ear canal 108), may deform ear canal wall 110.The deformation may, for example, stretch ear canal wall 110 and mayplace the skin layer under tension. Accordingly, it may be desirable toconfigure earpiece devices to be inserted within cartilaginous region116. Earpiece devices may be inserted (and expanded) in cartilaginousregion 116 without inducing discomfort and pain.

In general, ear canal 108 may vary substantially in shape and size overthe human population. In general, ear canal 108 is not straight orregularly shaped. Although not illustrated in FIG. 1, ear canal 108typically includes an upward tilt of approximately 45 degrees, such thattympanic membrane 112 is above the opening (i.e., dashed line 106) ofear canal 108. Ear canal 108 typically includes a first bend near theopening to ear canal 108 and a second bend that is proximate to tympanicmembrane 112.

Because the volume, shape, and length of ear canal 108 may substantiallyvary, there has been difficulty in providing a system that mayeffectively seal ear 100, attenuate noise, mitigate the occlusioneffect, operate under different environmental conditions, and may fit amajority of the population. For example, hearing aid manufacturerstypically generate a full custom earpiece for individuals that include amold of the patient's ear canal. The ear canal mold is then used to forma hearing aid housing. The procedure to create an ear canal mold iscostly, cumbersome, and is not easily adaptable for high volumeproduction.

Referring next to FIG. 2, a cross section diagram of an exemplaryearpiece device 200 is shown. Earpiece device 200 is shown relative toear 100. Earpiece device 200 may include occlusion section 202 andhousing unit 204 coupled to occlusion section 202. Occlusion section 202may be configured to be inserted in ear canal 108, at a location betweenthe entrance to the ear canal 108 and tympanic membrane 112. Asdiscussed above, it may be desirable to position occlusion section 202within cartilaginous region 116 (FIG. 1) of ear canal 108. Housing unit204 may be positioned outside of ear canal 108. In FIG. 2, housing unit204 is illustrated as being disposed in ear 100. It is understood thathousing unit 204 may also be configured to be placed behind ear 100 ormay be placed partially behind ear 100 and partially in ear 100.

Occlusion section 202 may include insertion element 206 and expandableelement 208. Insertion element 206 may be coupled to expandable element208 and may be used to position expandable element 208 in ear canal 108.Expandable element 208 is configured to be expanded, via medium 228. Ingeneral, expandable element 208 may be configured to form an acousticseal with a portion of ear canal wall 110. Expandable element 208 may beconfigured to partially or fully occlude ear canal 108, to providevarious degrees of acoustic isolation (i.e., attenuation of one or morefrequencies of ambient sound) at tympanic membrane 112.

In operation, expandable element 208 may be inserted in ear canal 108 ina contracted state. After insertion, expandable element 208 may besubsequently expanded (e.g., by being filled with medium 228), such thatexpandable element 208 conforms to ear canal 108 and forms at least apartial acoustic seal with ear canal 108. To remove earpiece device 200,expandable element 208 may be contracted (e.g., by removing at leastpart of medium 228) back to the contracted state. Accordingly, earpiecedevice 200 may then be easily removed from ear canal 108.

Expandable element 208 may be formed from any compliant material thathas a low permeability to medium 228. Examples of materials ofexpandable element 208 include any suitable elastomeric material, suchas, without being limited to, silicone, rubber (including syntheticrubber) and polyurethane elastomers (such as Pellethane® andSantoprene™) Materials of expandable element 208 may be used incombination with a barrier layer (for example, a barrier film such asSARANEX™), to reduce the permeability of expandable element 208. Ingeneral, expandable element may be formed from any suitable materialhaving a range of Shore A hardness between about 5 A and about 30 A,with an elongation of about 500% or greater.

Medium 228 may include any suitable liquid, gas or gel capable ofexpanding and contracting expandable element 208 and that would maintaina comfortable level of pressure for a user of earpiece device 200.Examples of medium 228 include, for example, silicone, non or lowpermeable-based polymers, gels, fully-fluorinated liquids, ethyleneglycol, isopropyl alcohol, air or other gasses (for example sulfurhexafluoride (SF6) or hydrogen).

Insertion element 206 may be formed from, for example, thermoplasticelastomer (TPE) materials, materials having an elastomeric property(such as silicone), or other malleable materials capable of conformingto the ear canal. Expandable element 208 may be attached to insertionelement 206 via any suitable attachment method, such as, but not limitedto, bonding, adherence with an adhesive, thermal bonding, molding andultrasonic bonding.

Although expandable element 208 is illustrated as being of anannular-disc shape, it is understood that expandable element 208 may beformed of other shapes, such as conical-shaped, or toroidal-shaped.Although FIG. 2 illustrates a single expandable element 208, occlusionsection 202 may include multiple co-located expandable elements 208(such as an inner expandable element in an outer expandable element,where each expandable element 208 may be filled with different mediums228). Although FIG. 2 illustrates a single expandable element 208, it isunderstood that occlusion section 202 may include more than oneexpandable element 208 (for example, as shown in FIG. 8A), where eachexpandable element 208 may be filled with a same medium 228 or withdifferent mediums 228.

As described further below with respect to FIGS. 5-13, physicalparameters of occlusion section 202 may be selected to provide apredetermined sound attenuation characteristic over a frequency band.For example, a compliance of expandable element 208, the type of medium228, as well as the number of expandable elements 208, may be used todesign occlusion section 202 with a specific sound attenuationcharacteristic (such as a high pass filter or a low pass filter).According to an embodiment of the present invention, an amount ofexpansion pressure (of medium 228) with which expandable element 208 isexpanded may also be selected to control the amount of overall soundattenuation, as well as the amount of occlusion, over the frequencyband. In general, the expansion pressure may produce between about a 15%to about a 60% increase in atmospheric pressure.

For example, sleep apnea is an example of a noisy environment that canhave an impact on the health of the listener. Because snoring typicallyhas a large portion of its power in the lower frequencies in theacoustic range, a listener subjected to snoring could benefit from ahigh pass filter earpiece that allows higher frequencies of the acousticsignal to be transmitted through the earpiece, while attenuating thelower frequencies.

Housing unit 204 may include inflation management system 210 forcontrolling the transfer of medium 228 to and from occlusion section202, for expanding and contracting expandable element 208. Housing unit204 may also include user interface 212 coupled to inflation managementsystem 210. Inflation management system 210 may be activated responsiveto user interface 212, in order to expand and contract expandableelement 208. Housing unit 204 may also include further electricalcomponents. Inflation management system may include any suitable systemcapable of transferring medium 228 to and from expandable element 208.For example, inflation management system may include a pump actuator anda valve housing (not shown).

According to one embodiment, earpiece device 200 may include inflationmanagement system 210 and user interface 212, without anyelectro-acoustic elements. In this example embodiment, earpiece device200 may be configured simply as a sound isolation device, with apredetermined sound attenuation characteristic selected according to thephysical parameters of occlusion section 202.

According to another embodiment, housing unit 204 may include electricalcomponents as well as one or more electro-acoustical components. Forexample, housing unit 204 may include speaker 214, controller 220,memory 222, battery 224 and communication unit 226.

Speaker 214, memory 222, communication unit 226, user interface 212 andinflation management system 210 may be controlled by controller 220.Controller 220 may include, for example, a logic circuit, a digitalsignal processor or a microprocessor.

Communication unit 226 may be configured to receive and/or transmitsignals to earpiece device 200. Communication unit 226 may be configuredfor wired and/or wireless communication with an external device (e.g.,an MPEG player or a mobile phone).

Battery 224 may power the electrical and electro-acoustic components inhousing unit 204. Battery 224 may include a rechargeable or replaceablebattery.

The acoustic seal provided by occlusion section 202 may significantlyreduce a sound pressure level at tympanic membrane 112 from an ambientsound field at the entrance to ear canal 108 (to provide soundisolation). For example, occlusion section 202 having a high pass filtercharacteristic may substantially attenuate lower frequencies. Because ofthe sound isolation of occlusion section 202, speaker 214 may generate afull range bass response time when reproducing sound in earpiece device200.

According to another embodiment, housing unit 204 may include an earcanal (EC) microphone 216 located adjacent to speaker 214, which mayalso be acoustically coupled to ear canal 108. EC microphone 216 may beconfigured to measure a sound pressure level in ear canal 108. The soundpressure level in ear canal 108 may be used, for example, to test thehearing acuity of a user, to confirm an integrity of the acoustic seal,and/or to confirm the operation of EC microphone 216 and speaker 214.

According to another embodiment, housing unit 204 may include ambientmicrophone 218, as well as EC microphone 216 and speaker 214. Ambientmicrophone 218 may be configured to monitor a sound pressure of theambient environment at the entrance to ear 100. In at least oneexemplary embodiment, earpiece device 200 may actively monitor a soundpressure level both inside and outside ear canal 108 and may enhancespatial and timbral sound quality, while maintaining supervision toensure safe sound reproduction levels. Earpiece device 200, in variousembodiments may conduct listening tests, filter sounds in theenvironment, monitor sounds in the environment, present notificationbased on the monitored sounds, maintain constant audio content toambient sound levels, and/or filter sound in accordance with apersonalized hearing level.

Earpiece device 200 may be configured to generate an ear canal transferfunction (ECTF) to model ear canal 108 (via speaker 214 and ECmicrophone 216), as well as an outer ear canal transfer function (OETF)(via ambient microphone 218). Earpiece device 200 may be configured todetermine a sealing profile with ear 100 to compensate for any acousticleakage. Earpiece device 200 may be configured to monitor a soundexposure to ear canal 108 (for example, from speaker 214 as well as fromambient noise measured via ambient microphone 218).

Referring to FIG. 3, a cross section diagram of earpiece device 200 isshown, which illustrates further components of insertion element 206. InFIG. 3, only some of the components of housing unit 204 are shown, forconvenience. According to an exemplary embodiment, insertion element 206may include pneumatic channel 302. Pneumatic channel may be coupled toexpandable element 208 and to inflation management system 210. Pneumaticchannel 302 may be used to transfer medium 228 (illustrated by doubleheaded arrow A) to and from expandable element 208 via port 308.

In at least one exemplary embodiment, insertion element 206 may includeat least one acoustic channel (e.g., acoustic channel 304 and/oracoustic channel 306) for receiving or delivering audio content. Forexample, housing unit 204 may include speaker 214. Insertion element 206may, thus, include acoustic channel 304 for delivering sound fromspeaker 214 to ear canal 108. As another example, housing unit 204 mayinclude speaker 214 and EC microphone 216. In this example, insertionelement 206 may include acoustic channels 304, 306, respectively coupledto speaker 214 and EC microphone 216. Acoustic channel 306 may deliversound from ear cana1108 to EC microphone 216.

As described above, expandable element 208 may form an acoustic sealwith ear canal wall 110 at a location between the entrance to ear canal108 and tympanic membrane 112. The acoustic seal by expandable element208 may substantially attenuate sound in ear canal 108 from the ambientenvironment (thus providing sound isolation to ear canal 108). Insertionelement 206 may also include one or more acoustic channels (e.g.,acoustic channel 304 and/or acoustic channel 306) for acousticallycoupling sound between ear canal 108 and one or more respectivetransducers (e.g., speaker 214 and/or EC microphone 216). Accordingly,sound transmitted to and/or from ear canal 108 via acoustic channel 304(and/or 306) may be substantially isolated from the ambient environment.

Referring next to FIGS. 4A-4D, exemplary earpiece device 200′ is shown.In particular, FIG. 4A is a perspective view diagram of earpiece device200′ with expandable element 208 in an expanded state; FIG. 4B is across section diagram of earpiece device 200′ with expandable element208 in the expanded state: FIG. 4C is a perspective view diagram ofearpiece device 200′ with expandable element 208 in a contracted state;and FIG. 4D is a cross-section diagram of earpiece device 200′ withexpandable element 208 in the contracted state.

Earpiece device 200′ is similar to earpiece device 200 except thatearpiece device 200′ includes flange 402 coupled to insertion element206 of occlusion section 202. Flange 402 may provide sound attenuation(in addition to the sound attenuation by expandable element 208). Flange402 may also help to seat occlusion section 202 in ear canal 108 (FIG.2). Flange 402 may be formed of materials similar to expandable element208.

The selection of physical parameters of occlusion section 202 (FIG. 2)to provide predetermined sound attenuation characteristics is describedbelow.

It is often possible and convenient to represent an acoustical systemwith a lumped element model, as an acoustical circuit analogous to anelectrical circuit. For example, an acoustical system may be representedas an acoustic impedance (or acoustic mobility). In acoustic impedanceanalogs, for example, the sound pressure and volume velocity correspondto voltage and current, respectively. For example, occlusion section 202(FIG. 2) in ear canal 108 may be modeled by an acoustical impedancecircuit.

Referring to FIGS. 5A and 5B, an equivalent acoustical elementrepresentation of balloon 502 (an example of an expandable element)filled with medium 510 in tube 504 is described. In particular, FIG. 5Ais a cross section diagram of balloon 502 in tube 504; and FIG. 5B is anexample of a volume of one face of balloon 502 (for example, face 508)with pressure difference.

Balloon 502 and medium 510 may each be represented as acousticalelements. Because balloon 502 is within tube 504, the band of balloonmaterial in contact with tube walls 506 does not move. This effectivelyseparates balloon 502 into two parts, upstream face 508 and downstreamface 512. It is understood that the acoustical element representation ofdownstream face 512 is the same as that of upstream face 508. Thus, onlyupstream face 508 is considered below.

Face 508 of balloon 502 (filled with medium 510) includes a static DCpressure P2 on the outside and a static interior pressure Pg. If theoutside pressure is changed to P2′, there will be a change in the staticequilibrium of the balloon. Face 508 moves to a new position and mayhave a different shape (represented as face 508′), sweeping out a volumeΔV. Thus, the interior pressure will change to a new value Pg′. Theshape of the balloon face 508 is controlled by the difference inpressure across the material, i.e., P_(D)=P₂−P_(g) andP_(D)′=P₂′−P_(g)′.

Although, in general, the relationship between the change in pressuresand the volume of balloon 502 may be complicated, for the acousticalbehavior, it is assumed that these changes are very small, so that asimple acoustical representation of balloon 502 may be determined.

FIG. 5B illustrates an example of the volume change of face 508 ofballoon 502 with a change in pressure difference across the material.Over a small change in pressure difference ΔP_(D), the curve is verynearly linear and the volume change ΔV may be represented as:

$\begin{matrix}{{\Delta V} \approx {\left( \frac{\partial V}{\partial P_{D}} \right)_{P_{d}}\Delta P_{D}} \equiv {C_{2}\Delta P_{D}}} & (1)\end{matrix}$

For acoustic pressures, the pressures acting on face 508 may beconsidered to oscillate sinusoidally in time about their static values,and may be represented by complex notation as

$\begin{matrix}{{P_{2}^{\prime} = {P_{2} + {{Re}\left\{ {p_{2}e^{i\omega t}} \right\}}}}{P_{g}^{\prime} = {P_{g} + {{Re}\left\{ {p_{g}e^{i\omega t}} \right\}}}}} & (2)\end{matrix}$

where P_(g) and P₂ are the (complex) sound pressures on either side ofthe balloon section, so that

$\begin{matrix}{{\Delta P_{D}} = {{Re}\left\{ {\left( {p_{2} - p_{g}} \right)e^{i\omega t}} \right\}}} & (4)\end{matrix}$

Similarly, the volume changes harmonically as

$\begin{matrix}{{\Delta V} = {{V^{\prime} - V} = {{Re}{\left\{ {V*e^{i\omega t}} \right\}.}}}} & (5)\end{matrix}$

where Vis the static volume enclosed by face 508 of the balloon. Thus,the volume velocity U (i.e., the rate change of volume with time) may berepresented as

$\begin{matrix}{{U \equiv {{Re}\left\{ {u_{2}e^{i\omega t}} \right\}}} = {\frac{dV^{\prime}}{dt} = {{Re}\left\{ {i\omega V*e^{i\omega t}} \right\}}}} & (6)\end{matrix}$

Accordingly, the sound pressure difference is related to the complex tovolume velocity u₂, as

$\begin{matrix}{{p_{2} - p_{g}} = \frac{u_{2}}{i\omega C_{2}}} & (7)\end{matrix}$

where C2 is the acoustical capacitance of one side (for example face508) of balloon 502. The value of capacitance C2 may be determined bythe slope of the tangent line in FIG. 5B.

Medium 510 may include, for example, a gas or a liquid. The acousticalelement representation of medium 510 may be different depending onwhether medium 510 is a gas or a liquid. The consideration of medium 510as a liquid is discussed with respect to FIG. 12. The acousticalrepresentation of medium 510 that includes a gas is considered below.Accordingly, medium 510 is referred to below as gas 510.

An enclosed volume of gas may store energy in its compressions. Thus,gas 510 (for example, air) within balloon 502 may also be represented asan acoustic capacitance. The volume velocity u2, as defined, acts tocompress gas 510 contained within balloon 502. The volume velocitycorresponding to face 512 of balloon 502 may be defined in the oppositesense, such that the volume velocity u1 acts to uncompress the air. Thenet volume velocity (uru1) is related to the sound pressure p9 insidethe balloon by:

$\begin{matrix}{{u_{2} - u_{1}} = {i\omega C_{g}p_{g}}} & (8)\end{matrix}$

where capacitance C9 is given by:

$\begin{matrix}{C_{g} = \frac{V_{9}}{\gamma P_{9}}} & (9)\end{matrix}$

and where Vg is the enclosed volume, P_(g)⋅ is the static pressureinside balloon 502, and γ is the specific heat ratio.

Referring to FIGS. 6A and 6B, acoustical system 600 representing anexpandable element in an ear canal is shown. In particular, FIG. 6A is across section diagram of acoustical system 600 including balloon 502 intube 504 having anechoic termination 602; and FIG. 6B is anelectro-acoustical circuit diagram of acoustical system 600. Acousticalsystem 600 represents an expandable element (balloon 502) in an earcanal (tube 504) having a tympanic membrane (anechoic termination 602).Although not illustrated, balloon 502 may be formed on an insertionelement (such as insertion element 206 shown in FIG. 2).

If the lateral dimensions of tube 504 are less than a wavelength ofsound, sound waves may propagate along both forward and backwardlongitudinal directions. Because tube 504 includes anechoic termination602, there are no reflected sound waves, only forward propagating waves.

Consider pressure p₁ and volume velocity u₁ at a position in tube 504.For a plane wave traveling in a single direction, the pressure and thevolume velocity are in phase and are related as:

$\begin{matrix}{p_{1} = {R_{c}u_{1}}} & (10)\end{matrix}$

where the characteristic acoustical resistance of tube 504 (at anechoictermination 602) is

$\begin{matrix}{R_{c} = \frac{\rho c}{A}} & (11)\end{matrix}$

Here, A is the internal cross-sectional area of tube 504, ρ is thedensity of the gas (e.g., air), and c is the sound speed in the gas(e.g., air).

As discussed above, faces 508, 512 of balloon 502 may each berepresented as acoustical compliance C_(b). Gas 510 within balloon 502may be represented as acoustical compliance C_(g). Finally, tube 504with anechoic termination 602 may be represented as resistance R_(c).

Based on the acoustical elements representing balloon 502, gas 510 andtube 504, acoustical system 600 may be represented as an equivalentelectro-acoustical circuit (i.e., an acoustical impedance analog), asshown in FIG. 6B. Thus capacitance C_(b) of face 508 receives pressurep₂. Capacitance C_(b) is coupled to capacitance C_(g) of gas 510 andcapacitance C_(b) of face 512. Capacitance C_(b) of face 512 is coupledto resistance R_(c) of the termination of tube 504. Thus, pressure p₂ isprovided at an output terminal of the circuit. It is understood that theelectro-acoustic circuit may be modified to account for the finite sizeof insertion element 206 (FIG. 2) on which balloon 502 may be mounted.

Network methods may be applied to calculate the various quantities ofthe acoustical elements if values for the various circuit elements areavailable. Both R_(c) and C_(b) may be determined from the expressionsprovided above.

For a sample calculation, it is assumed that tube 504 has an innerdiameter of 9.53 mm (0.375″) and that balloon 502 contains a volume of0.713 cm3 at an inflation pressure of 300 mbar. Capacitance C_(b)corresponding to each face of balloon 502 may be determined, forexample, based on a calculation of the inflation dynamics of balloonmaterials, taking into account the Mooney-Rivlin type of stress-strainrelationship. In the sample calculation, several different values ofcapacitance including C_(b)=0.3C_(g), C_(b)=C_(g), and C_(b)=3C_(g) areselected. The transmission coefficient of acoustical energy may bedetermined as:

$\begin{matrix}{T = {20\log{❘\frac{p_{1}}{p_{2}}❘}}} & (12)\end{matrix}$

Referring to FIG. 7, the calculated transmission coefficients for thesethree values of capacitance C_(b) are shown. Curves 702, 704 and 706represent capacitance values C_(b)=3C_(g), C_(b)=C_(g), andC_(b)=0.3C_(g), respectively. All curves show about a 6 decibel (dB) peroctave drop off at the lower frequencies. Accordingly, balloon 502 actsas a first order high-pass filter.

Referring next to FIGS. 8A and 8B, acoustical system 800 is shown, whichrepresents two expandable elements in an ear canal. In particular, FIG.8A is a cross section diagram of acoustical system 800 includingballoons 802-A, 802-B in tube 504 having anechoic termination 602; andFIG. 8B is an electro-acoustical circuit diagram of acoustical system800. Balloons 802-A, 802-B are filled with gas 808-A, 808-B.

Acoustical system 800 is similar to acoustical system 600 (FIGS. 6A and6B), except that acoustical system 800 includes two balloons 802-A,802-B (i.e., two expandable elements), and balloons 802-A, 802-B areillustrated as being mounted on insertion element 804. Two balloons802-A, 802-B may be formed, for example, from a single balloon materialattached to insertion element 804 at attachment points 805 and 806. Inan exemplary embodiment, attachment point 806 represents an 0-ringapproximately midway along a length of a single balloon. As anotherexample, balloons 802-A, 802-B may be formed from different balloonmaterials attached at respective attachment points 805, 806. Gas 808-Bmay be the same as gas 808-A or may be different from gas 808-A.

Balloons 802-A, 802-B have respective volumes of V_(A) and V_(b), withrespective sound pressures of P_(A) and P_(b). Gap 810 between balloons802-A, 802-B (at attachment point 806) has volume V_(c) and soundpressure Pc. The motion of the right-hand face of balloon 802-A includesa volume velocity u_(A). Similarly, the motion of the left-hand face ofballoon 802-B includes a volume velocity u_(B).

Based on the acoustical elements described above for balloon 502 (FIGS.6A and 6B), gas 510 and tube 504, acoustical system 800 may also berepresented as an equivalent electro-acoustical circuit (i.e., anacoustical impedance analog), as shown in FIG. 8B. Thus, capacitancesC_(bA1), C_(gA), C_(bA2) are associated with the left face of balloon802-A, gas 808-A and the right face of balloon 802-A, respectively.Capacitance Cc is associated with gap 810. Capacitances C_(bB1), C_(gB),C_(bB2) are associated with the left face of balloon 802-B, gas 808-Band the right face of balloon 802-B, respectively. Although not shown,it is understood that the electro-acoustic circuit shown in FIG. 8B maybe modified to account for insertion element 804.

Referring to FIG. 9, example transmission coefficients are shown for theelectro-acoustical circuit shown in FIG. 8B, using several differentvalues of capacitance. In this example, both balloons 802-A, 802-B havea volume of 0.222 cm3 and an inflation pressure of 300 mbar, so thatC_(gA)=C_(gB). Gap 810 between balloons 802-A, 802-B is at atmosphericpressure and has a volume of 0.095 cm3. Three different selections ofballoon capacitances are used. For curve 902, the capacitances areC_(bA1)=C_(bA2)=C_(bB1)=C_(bB2)=3C_(gA). For curve 904, the capacitancesare C_(bA1)=C_(bB1)=3C_(gA) and C_(bA2)=C_(bB2)=C_(gA). For curve 904,the capacitances are C_(bA1)=C_(bA2)=C_(bB1)=C_(bB2)=C_(gA).

As shown in FIG. 9, the acoustical transmission for two balloons 802-A,802-B is similar to the acoustical transmission of a single balloon(shown in FIG. 7). Thus, similar to the single balloon (FIG. 7), thecombination of two balloons 802-A, 802-B also acts like a first-orderhigh-pass filter, with approximately a 6 dB/octave slope at lowfrequencies.

FIG. 8A illustrates acoustical system 800 including two balloons 802-A,802-B disposed along a length of insertion element 804 (i.e., in seriesarrangement, as illustrated in FIG. 8B). According to anotherembodiment, balloons 802-A, 802-B may be co-located on insertion element804. Balloons 802-A, 802-B, thus, may be formed in a parallelarrangement.

Measurements on several double balloons, however, have revealed a morecomplicated variation with frequency. This variation may be due to smallleaks between balloons 802-A, 802-B.

Referring next to FIGS. 10A and 10B, acoustical system 1000 is shown,which represents two expandable elements in an ear canal. In particular,FIG. 10A is a cross section diagram of acoustical system 1000 includingballoons 802-A, 802-B in tube 504 having anechoic termination 602; andFIG. 10B is an electro-acoustical circuit diagram of acoustical system1000. Acoustical system 1000 is similar to acoustical system 800 (FIGS.8A and 8B), except that acoustical system 1000 includes leak 1002 atattachment point 806.

Leak 1002 may be modeled as a short, circular passage between balloons802-A, 802-B. The volume velocity entering leak 1002 is represented asu_(LA) and the volume velocity exiting leak 1002 is represented asu_(LB). A volume of fluid (gas or liquid) that has a length comparableor greater than a wavelength (or a radius that is comparable or smallerthan a viscous boundary layer thickness) may not be capable of beingtreated as a simple volume. Accordingly, a general theory is describedbelow for acoustical propagation along a circular passage (i.e., leak1002).

Consider that leak 1002 is a hollow, circular passage of radius a_(L)and length l At one end of leak 1002, there is a pressure p_(A) andvolume velocity u_(LA); at the other end, there is a pressure p_(B) andvolume velocity u_(LB). These quantities are related, generally, througha transfer matrix T_(L) as:

$\begin{matrix}{\begin{bmatrix}p_{A} \\u_{LA}\end{bmatrix} = {{T_{L}\begin{bmatrix}p_{B} \\u_{LB}\end{bmatrix}} = {\begin{bmatrix}{\cosh{\Gamma\ell}} & {Z\sinh{\Gamma\ell}} \\{Z^{- 1}\sinh{\Gamma\ell}} & {\cosh{\Gamma\ell}}\end{bmatrix}\begin{bmatrix}p_{B} \\u_{LB}\end{bmatrix}}}} & (13)\end{matrix}$

Where

$\begin{matrix}{\Gamma = {i\frac{\omega}{c}\sqrt{\frac{T_{\alpha}}{T_{\beta}}}}} & (14) \\{Z = \frac{\rho c}{\pi a_{L}^{2}\sqrt{T_{\alpha}T_{\beta}}}} & (15)\end{matrix}$

Where

$\begin{matrix}{T_{\alpha} = {1 + \frac{2\left( {\gamma - 1} \right){J_{1}\left( {\alpha_{L}\alpha} \right)}}{\alpha_{L}\alpha{J_{0}\left( {\alpha_{L}\alpha} \right)}}}} & (16) \\{T_{\beta} = {1 - \frac{2{J_{1}\left( {\alpha_{L}\beta} \right)}}{\alpha_{L}\beta{J}_{0}\left( {\alpha_{L}\beta} \right)}}} & (17) \\{\alpha = \sqrt{\frac{{- i}\rho\omega N_{pr}}{\mu}}} & (18) \\{\beta = \sqrt{\frac{{- i}\rho\omega}{\mu}}} & (19)\end{matrix}$

where μ represents the coefficient of viscosity of the gas (e.g., air),γ represents the ratio of specific heats, N_(pr) represents the Prandtlnumber and J₀(*), J₁(*) represent Bessel functions of the first kind forrespective integer orders 0 and 1.

Leak 1002 that is a circular tube, in general, does not have a simplelumped-element representation. However, leak 1002 may be represented asa network block in an electro acoustical circuit. Accordingly, based onthe acoustical elements described above, acoustical system 1000 havingleak 1002 may also be represented as an equivalent electro-acousticalcircuit (i.e., an acoustical impedance analog), as shown in FIG. 10B. InFIG. 10B, network block 1004 with transfer matrix TL represents leak1002. The circuit shown in FIG. 10B is similar to the circuit shown inFIG. 8B, except for the inclusion of network block 1004. Network block1004 may act in parallel to some of the circuit elements representingballoons 802-A, 802-B.

Referring to FIG. 11, example transmission coefficients are shown forthe electro-acoustical circuit shown in FIG. 10B, using severaldifferent leak sizes (and eq. (13) for the transfer matrix TL). The leaksizes include radii of 0 cm (i.e., no leak), 0.017 cm, 0.05 cm and 0.1cm. In particular, curves 1102, 1104, 1106 and 1108 represent respectiveleak sizes of 0 cm, 0.017 cm, 0.05 cm, and 0.1 cm. As shown in FIG. 11,there is a transition from one type of behavior to another with leaksize. For a large radius leak (curve 1108), acoustical system 1000effectively represents a single large balloon, with a 6 dB/octave dropat low frequencies. For a zero leak (curve 1102), acoustical system 1000represents a double balloon system, also with a 6 dB/octave lowfrequency behavior. At intermediate sized leaks (curves 1104 and 1106),acoustical system 1000 transitions from a single balloon mode at lowfrequencies to a double balloon mode at high frequencies, thus producinga more complex frequency variation over approximately the 200 Hz-2000 Hzrange. In the example shown in FIG. 11, the attenuation is relativelyflat for the 0.017 cm leak (curve 1104). Accordingly, it may be possibleto design leaks between balloons 802-A, 802-B to selectively shape thetransmission (and attenuation) to a desired response over a range offrequencies.

Referring next to FIGS. 12A-12C, acoustical system 1200 is shown, whichrepresents a liquid-filled expandable element in an ear canal. Inparticular, FIG. 12A is a cross section diagram of acoustical system1200 including balloon 502 filled with liquid 1202 in tube 504 havinganechoic termination 602; FIG. 12B is a circuit diagram of a transfernetwork associated with balloon 502 filled with liquid 1202; and FIG.12C is an electro-acoustical circuit diagram of acoustical system 1200.

Acoustical system 1200 is similar to acoustical system 600 (FIGS. 6A and6B), except that acoustical system 1200 includes balloon 502 filled withliquid 1202. Filling balloon 502 with liquid 1202 (for example, waterinstead of air), may change the acoustical behavior of balloon 502. Ifballoon 502 is of sufficiently short length, it may be treated as asmall volume (similar to holding a volume of gas as described above).For balloon 502 having a length comparable to a wavelength, balloon 502may be treated as a transmission line. This may be the case for liquid1202, because the sound speed in liquids is considerably higher than inair, such that the wavelengths are correspondingly longer.

The pressure just inside face 508 of balloon 502 is represented as p_(A)and the pressure just inside face 512 is represented as p_(B). Let L bethe length of the balloon and α, the internal diameter of theconstraining tube. The sound pressures (p_(A), p_(B)) and volumevelocities (u₁, u₂) may be related through a transfer matrix T_(liq) by:

$\begin{matrix}{\begin{bmatrix}p_{A} \\u_{2}\end{bmatrix} = {{T_{liq}\;\begin{bmatrix}p_{B} \\u_{1}\end{bmatrix}} = {\begin{bmatrix}{\cos\; h\;\Gamma\;\ell} & {Z\;\sin\; h\;\Gamma\;\ell} \\{Z^{- 1}\;\sin\; h\;{\Gamma\ell}} & {\cos\; h\;\Gamma\;\ell}\end{bmatrix}\begin{bmatrix}p_{B} \\u_{1}\end{bmatrix}}}} & (20)\end{matrix}$

If a is sufficiently large, viscous and thermal boundary layer effectsmay be ignored, such that the arguments aα and aβ are also large andT_(α)≈T_(β)≈1. Then,

$\begin{matrix}{\begin{bmatrix}p_{A} \\u_{2}\end{bmatrix} = {\begin{bmatrix}{\cos\;{kL}} & {{iZ}_{liq}\;\sin\;{kL}} \\{{iZ}_{liq}^{- 1}\;\sin\;{kL}} & {\cos\;{kL}}\end{bmatrix}\begin{bmatrix}p_{B} \\u_{1}\end{bmatrix}}} & (21)\end{matrix}$

where k=w/cliq is the wavenumber and Z_(liq) is the characteristicimpedance of the liquid, given as

$\begin{matrix}{Z_{liq} = \frac{\rho_{liq}c_{liq}}{\pi a^{2}}} & (22)\end{matrix}$

As shown in FIG. 12B, eq. (21) may be represented as a transfer network.For the transfer network:

$\begin{matrix}{Z_{1} = {Z_{2} = {Z_{3}\left( {{\cos{kL}} - 1} \right)}}} & (23)\end{matrix}$

where

$\begin{matrix}{Z_{3} = \frac{Z_{liq}}{i\;\sin\;{kL}}} & (24)\end{matrix}$

If it is further assumed that kL is small, the expressions simplifyfurther, yielding

$\begin{matrix}{Z_{1} = {Z_{2} = {i\omega L_{liq}}}} & (25)\end{matrix}$

Where

$\begin{matrix}{Z_{3} = \frac{1}{i\omega C_{liq}}} & (26)\end{matrix}$

In eqs. (25) and (26), L_(liq) represents an inductance and C_(liq)represents a capacitance, respectively, where:

$\begin{matrix}{L_{liq} = \frac{\rho_{liq}L}{\pi a^{2}}} & (27) \\{C_{liq} = \frac{\pi a^{2}L}{\rho_{liq}c_{liq}^{2}}} & (28)\end{matrix}$

The inductance L_(liq) is directly related to the mass of the liquidcontained in the volume. The capacitance C_(liq) is related to thecompliance of the liquid.

Accordingly, based on the acoustical elements described above, and thetransfer network shown in FIG. 12B, acoustical system 1200 may berepresented as an equivalent electro-acoustical circuit (i.e., anacoustical impedance analog), as shown in FIG. 12C. The circuit shown inFIG. 12C is similar to the circuit shown in FIG. 6B, except for theinclusion of inductances L_(liq), and the replacement of capacitanceC_(g) with capacitance C_(liq).

Referring to FIG. 13, example transmission coefficients are shown forthe electro-acoustical circuit shown in FIG. 12C, using several valuesof capacitance for a water-filled balloon. For the example, the balloonvolume is 0.713 cm³ and the constraining tube has an inner diameter of0.953 cm. The capacitance C_(b) of faces 508, 512 may be estimatedaccording to the following argument. The shape of balloon 502 oninflation may depend mainly on the pressure difference across themembrane and not on what liquid 1202 (e.g., water) balloon 502 contains.If water-filled balloon 502 is inflated to a volume comparable to thatof an air-filled balloon, there may be a comparable inflation pressure.In the example, the inflation pressure is selected as 300 mbar. Thecapacitances C_(b) include 3C_(g), C_(g), and 0.3C_(g). In particular,curve 1302 represents C_(b)=C_(g), curve 1304 represents C_(b)=0.3C_(g)and curve 1306 represents C_(b)=3C_(g). As shown in FIG. 13, thetransmission is quite low up to about 2 or 3 kHz. Curves 1302 and 1304include a low frequency resonance due to the mass of the water and thestiffness of the balloon material. In general, by filling balloon 502with liquid 1202, system 1200 may act as a low pass filter.

Referring generally to FIGS. 2 and 6A-13, exemplary occlusion sections202 of the present invention may be formed to produce a predeterminedsound attenuation characteristic over a frequency band, for an expandedstate of one or more expandable elements 208. The predetermined soundattenuation characteristic may be produced by selecting physicalparameters of occlusion section 202 (such as the material of expandableelement 208, medium 228, as well as the effects of insertion element206) in accordance with an electro-acoustical circuit model of occlusionsection 202 in ear canal 108. Thus, appropriate materials and mediumsmay be selected that substantially match acoustical elementcharacterizations of expandable element 208 and medium 228, to producethe predetermined sound attenuation characteristic. The predeterminedsound attenuation characteristic, in general, may include a firstfrequency range over which sound is substantially attenuated and asecond frequency range over which sound is substantially passed.

It is understood that a predetermined sound attenuation characteristicmay also be produced by combining multiple expandable elements 208 (withsimilar or different materials) filled with different mediums 228. Forexample, a first expandable element 208 filled with gas (to produce ahigh pass filter) may be coupled with a second expandable element 208filled with a liquid (to produce a low pass filter). The combination ofthe two expandable elements 208 with different mediums 228 may produce aband pass filter.

Referring next to FIG. 14A-14D, example attenuation characteristics forvanous parameters of a single expandable element in a tube are shown.FIG. 14A is a graph of effective attenuation as a function of frequencyfor various lengths of an expendable element. In FIG. 14A, results forlengths of 4 mm, 5 mm and 9 mm are illustrated. FIG. 14B is a graph ofeffective attenuation as a function of frequency for various gaugepressures in an expendable element. In FIG. 14B, the horizontal curveillustrates an unoccluded tube. The remaining curves illustrate variousgauge pressures in the expandable element. FIG. 14C is a graph ofeffective attenuation as a function of frequency for an expandableelement for various tube diameters. In FIG. 14C, results for tubediameters of 6.35 mm, 9.53 mm and 12.7 mm are shown. FIG. 14D is a graphof effective attenuation as a function of frequency for an expandableelement formed from different materials.

FIGS. 14A-14D illustrate the high pass filter characteristics ofexemplary expandable elements. FIG. 14B illustrates that the amount ofattenuation in the lower frequencies may depend upon the gauge pressure.FIG. 14D illustrates the effect of the material of the expandableelement on the filter characteristics.

Referring next to FIGS. 15-17, example attenuation characteristics fordifferent occlusion sections in a tube are shown. FIG. 15 is a graph ofeffective attenuation as a function of frequency for exemplary occlusionsections having one and two expandable elements. In FIG. 15, curve 1502represents an unoccluded tube, curve 1504 represents a single balloonand curve 1506 represents a double balloon. FIG. 16 is a graph ofeffective attenuation as a function of frequency for a single balloonfilled with air or water. In FIG. 16, curve 1602 represents anunoccluded tube, curve 1604 represents a balloon filled with air andcurve 1606 represents a balloon filled with water. FIG. 17 is a graph ofeffective attenuation as a function of frequency for exemplaryexpandable elements with and without a flange (as shown in FIGS. 4A-4D).In FIG. 17, curve 1702 represents an unoccluded tube, curve 1704represents a single balloon and curve 1706 represents a single balloonwith a flange.

FIG. 15 illustrates that both the single and double balloon have highpass filter characteristics. FIG. 16 illustrates the presence of a lowfrequency resonance in the water filled balloon (curve 1606). FIG. 17illustrates that the flange provides increased attenuation across thefrequency range compared with a balloon alone.

Although the invention is illustrated and described herein withreference to specific embodiments, the invention is not intended to belimited to the details shown. Rather, various modifications may be madein the details within the scope and range of equivalents of the claimsand without departing from the invention.

We claim:
 1. An earpiece sealing element, comprising: an insertionelement; a first occlusion section; a second occlusion section; and achannel connecting the first occlusion section with the second occlusionsection, wherein the channel is configured to leak medium between thefirst occlusion section and the second occlusion section, wherein a leakvalue is chosen so that the first occlusion section is configured sothat a first frequency bandwidth has a first attenuation value that is aflat attenuation throughout the first bandwidth within a first standarddeviation, and wherein the first occlusion section and second occlusionsection are connected to the insertion element.
 2. An earpiececomprising: an earpiece sealing element according to claim 1; amicrophone configured to measure an acoustic environment, creating asound signal; a speaker; a user interface; a memory that storesinstructions; and a logic circuit that executes the instructions toperform operations, the operations comprising: detecting a monitoredsound in the sound signal; and creating a notification value when themonitored sound is detected.
 3. The earpiece according to claim 2,further including the operations of: detecting a user's voice in thesound signal, where the monitored sound is the user's voice; extractingan audio signal of the user's voice; analyzing the audio signal todetermine a voice command; and initiating a response to the voicecommand.
 4. The earpiece according to claim 3, where the voice commandis to create an audio content wish list.
 5. The earpiece according toclaim 4, where the response is at least one of the following actions,purchase a song in the audio content list, delete a song from the audiocontent list, skip to the next song in the audio content list, add asong to the audio content list, and delete the audio content list. 6.The earpiece according to claim 3, where the voice command is to searchthe internet.
 7. The earpiece according to claim 3, where the voicecommand is to play audio from the internet.
 8. The earpiece according toclaim 3, where the voice command is to scan the internet for an audio.9. The earpiece according to claim 3, where the voice command is to playaudio from a radio station.
 10. The earpiece according to claim 2,further including the operations of: sending a sealing signal to thespeaker; measuring the sound signal while the sealing signal is beingplayed by the speaker; and sending a sealing notification to the user.11. The earpiece of claim 10, where the microphone is an ear canalmicrophone that measures an ear canal acoustic environment.
 12. Theearpiece of claim 10, where the microphone is an ambient soundmicrophone that measures an ambient acoustic environment.
 13. Theearpiece according to claim 10 where the sealing notification is avisual notification of the earpiece's seal quality.
 14. The earpieceaccording to claim 2, where the microphone is an ear canal microphonethat measures an ear canal acoustic environment creating an internalsound signal.
 15. The earpiece according to claim 14, furthercomprising: an ambient sound microphone.
 16. The earpiece according toclaim 14, further including the operations of: calculating the soundpressure level dosage of a user using the internal sound signal.
 17. Theearpiece according to claim 16, further including the operations of:notifying the user when the dosage exceeds a threshold.